The tumor suppressor protein p53 plays a central role in maintaining the integrity of the genome in a cell by regulating the expression of a diverse array of genes responsible for DNA repair, cell cycle and growth arrest, and apoptosis [May et al., Oncogene 18 (53) (1999) p. 7621-7636; Oren, Cell Death Differ. 10 (4) (2003) p. 431-442, Hall and Peters, Adv. Cancer Res., 68: (1996) p. 67-108; Hainaut et al., Nucleic Acid Res., 25: (1997) p. 151-157; Sherr, Cancer Res., 60: (2000) p. 3689-95]. In response to oncogenic stress signals, the cell triggers the p53 transcription factor to activate genes implicated in the regulation cell cycle, which thereby initiates either apoptosis or cell cycle arrest. Apoptosis facilitates the elimination of damaged cells from the organism, while cell cycle arrest enables damaged cells to repair genetic damage [reviewed in Ko et al., Genes & Devel. 10: (1996) p. 1054-1072; Levine, Cell 88: (1997) p. 323-331]. The loss of the safeguard functions of p53 predisposes damaged cells to progress to a cancerous state. Inactivating p53 in mice consistently leads to an unusually high rate of tumors [Donehower et al., Nature, 356: (1992) p. 215-221].
The p53 transcription factor promotes the expression of a number of cell cycle regulatory genes, including its own negative regulator, the gene encoding the Mouse Double Minute 2 (MDM2) protein [Chene, Nature Reviews Cancer 3: (2003) p. 102-109; Momand, Gene 242 (1-2): (2000) p. 15-29; Zheleva et al. Mini. Rev. Med. Chem. 3 (3): (2003) p. 257-270]. The MDM2 protein (designated HDM2 in humans) acts to down-regulate p53 activity in an auto-regulatory manner [Wu et al, Genes Dev., 7: (1993) p. 1126-1132; Bairak et al., EMBO J, 12: (1993) p. 461-468]. In the absence of oncogenic stress signals, i.e., under normal cellular conditions, the MDM2 protein serves to maintain p53 activity at low levels [Wu et al, Genes Dev., 7: (1993) p. 1126-1132; Barak et al., EMBO J, 12: (1993) p. 461-468]. However, in response to cellular DNA damage or under cellular stress, p53 activity increases helping to prevent the propagation of permanently damaged clones of cells by induction of cell cycle and growth arrest or apoptosis.
The regulation of p53 function relies on an appropriate balance between the two components of this p53-MDM2 auto-regulatory system. Indeed, this balance appears to be essential for cell survival. There are at least three ways that MDM2 acts to down-regulate p53 activity. First, MDM2 can bind to the N-terminal transcriptional activation domain of p53 to block expression of p53-responsive genes [Kussie et al., Science, 274: (1996) p. 948-953; Oliner et al., Nature, 362: (1993) p. 857-860; Momand et al, Cell, 69: (1992) p. 1237-1245]. Second, MDM2 shuttles p53 from the nucleus to the cytoplasm to facilitate the proteolytic degradation of p53 [Roth et al, EMBO J, 17: (1998) p. 554-564; Freedman et al., Mol Cell Biol. 18: (1998) p. 7288-7293; Tao and Levine, Proc. Natl. Acad. Sci. 96: (1999) p. 3077-3080]. Finally, MDM2 possesses an intrinsic E3 ligase activity for conjugating ubiquitin to p53 for degradation within the ubiquitin-dependent 26S proteosome pathway [Honda et al., FEBS Lett, 420: (1997) p. 25-27; Yasuda, Oncogene 19: (2000) p. 1473-1476]. Thus, MDM2 impedes the ability of the p53 transcription factor to promote the expression of its target genes by binding p53 in the nucleus. Attenuating the p53-MDM2 auto-regulatory system can have a critical effect on cell homeostasis. Consistently, a correlation between the overexpression of MDM2 and tumor formation has been reported [Chene, Nature 3: (2003) p. 102-109]. Functional inactivation of wild type p53 is found in many types of human tumors. Restoring the function of p53 in tumor cells by anti-MDM2 therapy would result in slowing the tumor proliferation and instead stimulate apoptosis. Not surprisingly then, there is currently a substantial effort being made to identify new anticancer agents that hinder the ability of HDM2 to interact with p53 [Chene, Nature 3: (2003) p. 102-109]. Antibodies, peptides, and antisense oligonucleotides have been demonstrated to destroy the p53 -MDM2 interaction, which would release p53 from the negative control of MDM2, leading to activation of the p53 pathway allowing the normal signals of growth arrest and/or apoptosis to function, which offers a potential therapeutic approach to treating cancer and other diseases characterized by abnormal cell proliferation. [See, e.g., Blaydes et al., Oncogene 14: (1997) p. 1859-1868; Bottger et al., Oncogene 13 (10): (1996) p. 2141-2147].
U.S. Pub. No. 2005/0037383 A1 describes modified soluble HDM2 protein, nucleic acids that code for this HDM2 protein, the crystals of this protein that are suitable for X-ray crystallization analysis, the use of the proteins and crystals to identify, select, or design compounds that may be used as anticancer agents, and some of the compounds themselves that bind to modified HDM2. (Schering-Plough Corp.).
Small molecules, said to antagonize the p53-MDM2 interaction, have been described. WO 00/15657 (Zeneca Limited) describes piperizine-4-phenyl derivatives as inhibitors of the interaction between MDM2 and p53. Grasberger et al. (J. Med. Chem., 48 (2005) p. 909-912) (Johnson & Johnson Pharmaceutical Research & Development L.L. C.) describes discovery and co-crystal structure of benzodiazepinedione as HDM2 antagonists that activate p53 in cells. Galatin et al. (J. Med. Chem. 47 (2004) p. 4163-4165) describes a nonpeptidic sulfonamide inhibitor of the p53-MDM2 interaction and activator of p53 dependent transcription in MDM2-overexpressing cells.
Chène (Molecular Cancer Research Vol. 2: (January 2006) p. 20-28) describes inhibition of the p53-MDM2 interaction by targeting the protein-protein interface. U.S. Pub. No. 2004/0259867 A1 and 2004/0259884 A1 describes Cis-imidazoles (Hoffmann La Roche Inc.) and WO2005/110996A1 and WO 03/051359 describes Cis-Imidazolines (Hoffmann La Roche Inc.) as compounds that inhibit the interaction of MDM2 with p53-like peptides resulting in antiproliferation. WO 2004/080460 A1 describes substituted piperidine compounds as MDM2-p53 inhibitors for treating cancer (Hoffmann La Roche Inc.). EP 0947494 A1 describes phenoxy acetic acid derivatives and phenoxy methyltetrazole that act as antagonists of MDM2 and interfere with the protein-protein interaction between MDM2 and p53, which results in anti-tumor properties (Hoffmann La Roche Inc.). Duncan et al., J. Am. Chem. Soc. 123 (4): (2001) p. 554-560 describes a p-53-MDM2 antagonist, chlorofusin, from a Fusarium Sp. Stoll et al., Biochemistry 40 (2) (2001) p. 336-344 describes chalcone derivatives that antagonize interactions between the human oncoprotein MDM2 and p53.
There is a need for effective inhibitors of the HDM2 or MDM2 protein in order to treat or prevent cancer, other disease states associated with cell proliferation, diseases associated with HDM2, or diseases caused by inadequate p53 activity. The present application discloses compounds that have potency in inhibiting or antagonizing the HDM2-p53 and MDM2-p53 interaction and/or activating p53 proteins in cells.
In its many embodiments, the present invention provides novel compounds having HDM2 or MDM2 antagonist activity, methods of preparing such compounds, pharmaceutical compositions comprising one or more of such compounds, methods of preparing pharmaceutical formulations comprising one or more of such compounds, potential methods of treatment or prevention of one or more diseases associated with HDM2, MDM2, p53, or p53 peptides by administering such compounds or pharmaceutical compositions.